Photographic processes and compositions useful therein



May 31, 1960 M. M. MORSE 2,938,792

PHOTOGRAPHIC PROCESSES AND COMPOSITIONS USEFUL THEREIN Filed March 12, 1957 Suppor'l' Silver Halide Sl'rcfurn Aqueous Solu'l'ion of Silver Halide Developer FIG. I

Silver Transfer Reversal p m, Comkuining E+ y n c K/ H1 20 hIOG er: '4

um -"i -l -22 FIG. 2

INVENTOR.

M 4 Ew m ATTORNEYS PHOTOGRAPHIC PROCESSES AND COMPOSITIONS USEFUL THEREIN Meroe M. Morse, Boston, Mass, assignor to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware Filed Mar. 12, 1957, Ser. No. 645,445

6 Claims. (Cl. 96-29) The present invention relates to photography and, more particularly, to the production of photographic prints by silver transfer reversal.

Silver transfer-reversal techniques generally involve subjecting a silver halide latent image to developing and dissolving reagents in the presence of a silver-receptive environment where a visible print is formed. For example, a fluid, such as an alkaline aqueous solution of a silver halide developer and solvent, is applied to a pair of strata, for example a photoexposed silver halide stratum and a silver-receptive stratum that are superposed. Thereafter, the strata are maintained in superposed relation for a predetermined processing period during which the reagents develop exposed silver halide to silver and react with unreduced silver halide to form a soluble silver complex that is reduced to silver in the print-receptive stratum to form a positive print. The present invention contemplates increasing the overall photographic speed of silver transfer-reversal techniques with the aid of an additive, initially disposed, for example, either in the fluid or on one of the sheets.

The primary object of the present invention is to increase the overall speed of a silver transfer-reversal process with the aid of a polyalcohol thioether.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the process involving the several steps and the relation and order of one or more of such steps with respect to each of the others and the composition possessing the features, properties and the relation of components which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing wherein:

Figure l is an exaggerated cross-sectional view of photographic materials undergoing a preferred process embodying the present invention; and

Fig. 2 is an exaggerated cross-sectional view of the print produced by the process of Fig. 1.

Generally, Fig. 1 shows a silver halide processing fluid 10 spread in a uniformly thin layer between the adjacent superposed surfaces of a silver halide photosensitive sheet 12 and a silver print-receptive sheet 14. Such spreading, for example, is accomplished by advancing the sheets, together with the fluid, between a pair of pressure-applying rollers. In accordance with the present invention,the processing fluid contains as an additive, an ethylenic thioether, for example, an alkyl poloxyetheylene thioether such as that sold by E. F. Houghton Co. under the trade name Cerfak 1300 or a polyethylene glycol tertdodecylthioether such as that sold by Sharples Chemical, Inc., under the trade name Nonic 218, in viscous alkaline solution with a silver halide developer such as .hydroquinone, a silver halide solvent such as sodium United States Patent thiosulfate and a thickener such as a water-soluble polymer or gum or an insoluble emulsifiable oil. Nome 218 is a non-ionic straw-colored liquid having a specific gravity of 1.05 (20/20 C.) and a viscosity of 1.33 potses (25 C.). It is soluble in water and at least 5 percent soluble in ethyl alcohol, acetone, ethyl acetate, arnyl acetate, diethyl ether and pyridine. Analyses have mdicated Nonic 218 to have a molecular weight on the order of about 730 and to contain about 12 oxyethylene groups (CH CH O). Cerfak 1300 is a non-iomc straw-colored liquid soluble in all proportions in water. The photosensitive sheet includes a gelatino silver hahde stratum 16 on a suitable support 18 and the print-receptive sheet includes a silver-receptive stratum 20 on a suitable support 22. Within a predetermined period after solution 10 is spread, the reagents therein form a negative print-in silver halide strtum 16 by reducing silver halide to silver and react with unreduced silver halide to form a silver complex which diffuses into the layer of processing fluid to silver-receptive stratum 20 where it is reduced to silver to form a positive print. The presence of the ethylenic thioether is responsible for the production of good positive prints at lower levels of exposure than would be necessary in its absence.

Example Grams Hydroquinone 52.0 Sodium thiosulfate 14.5 Nonic 218 43.0 Sodium hydroxide 54.6 Sodium sulfite 78.0 Sodium carboxymethyl cellulose 93.0 Water 1860.0

Here, silver halide stratum 12 and silver-receptive stratum 14 were maintained in superposed relation with processing fluid 10 therebetween for a period of approximately from 40 to 120 seconds in duration. At the end I of this period, silver-receptive stratum 14 and layer of solution 10 were stripped from silver halide stratum 12 to display a positive print of good quality, the overall photographic speed of this process being twice the overall speed of a process effected by the foregoining formulation without incorporation of Nonic 218.

The proportions of the ingredients of processing fluid 10 may be varied within wide limits. However, where the processing period is as specified, within the range of from 40 to 120 seconds in accordance with the now conventional duration of silver transfer-reversal processing periods, practical results are achieved where, by total weight of the fluid, the developer ranges from 1 to 8%, the silver halide solvent from .3 to 10%, and the thickenr is in suflicient cocentration to impart to the fluid a viscosity of from to 200,000 centipoises at a temperature of 23 C. Practical results are achieved when the ethylenic thioether ranges, by total weight of the fluid, from V3 to 3%.

The present invention may be applied to a variety of silver transfer-reversal processes other than the one specifically referred to above. The fluid may be spread either between the adjacent faces or on one of the reswam Y mote faces of "the superposed silver halide. silver-receptive strata before or after 'photoexposure. The fluid itself may contain a silver-receptivetagent in the presence of which print formationoccurs. Before photoexposure, such a process may provide a;s upport with a photosensitive coating by application of a'photosens'itive material in 1 accordance with the principles of application Serial iNp. 299,353,:fil6d3l1h'l'7 .1952, now Patent No. 2,846,- 130 9,intheuarne of "Edwin H. Land. Before photoexposure suc'h a process may initiate development to pro vide a dynamic photosensitive stratum in which a latent imagelater formed ,develops spontaneously in accordance with the principles of application Serial No. 498,672, iilefcl April 1, 1955, in the name of Edwin E. Land. The two sheetsmay be stripped apart to uncover the resulting print or may. :be retained in superposed relation, when the maximum density of the negative is small compared 'torthe maximum density of the positive print, in accordance withthe teaching of application Serial No. 466,889, filed November t, 1954, now Patent 'No. 2,861,885, in the name of Edwin H. 'Land. When the various materials are associated in the form of a-film unit having a pair of sheets and a container whose contents are to be spread between the sheets, the photographically active ,materials, including the ethylenic thioether, may be t carried at a variety offlocations in the container or on the sheets.

The present invention thus is based upon the discovery of the unique properties of ethylenic thioethers in relation to silver transfer-reversal processes and compositions useful therein.

Since certain changes may be made in the above process and composition without departing from the scope of the invention :herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is 1. The photographic process of applying an aqueous alkaline solution of a silver halide developer, a silver halide solvent and an alkyl polyoxyethylene thioether to an exposed silver halide stratum and a silver-receptive stratum in superposed relation in order to produce a 7 veloper, from about 0.3"to about 10% silver halide'solvent and fromabout 0.33 to about 3% of said alkyl poly- -oxyethylene thioether.

2. The photographic process of applying an aqueous alkaline solution of a silver halide developer, a silver halide solvent and a polyethylene glycol tertiary dodecylthioether to an exposed silver halide stratum and a silver-receptive stratum in superposed relation in order to produce .a silver transfer print, said solution comprising, by total weight of the solution, from about 1 to about 8% developer, from about 0.3 to about 10% silver halide solvent and from about 03310 about 3% of said thioether.

3. A photographic composition for silver transfer reversal processes comprising an-aqueous alkaline solution 0E a silver halide developer, a silver halide solvent and an alkyl polyoxyethylene thioether for increasing the speed of said silver transfer reversal processes, said solution including, by total weight of the solution, from about 1- 6 about 8% developer, from about 0.3 toabout 10% silver halide solvent and from about 0.33 to about 3% of said alkyl polyoxyethylene thioether.

4; A photographic composition for silver transfer reversal processes'comprising an aqueous alkaline solution of a silver halide developer, a silver halide solvent and a polyethylene glycol tertiary dodecylthioether, saidsolution including, by total weight of the solution, from about 1 to about 8% developer, from about 0.3 to about 10% silver halide solvent and from about 0.33 to about 3% of said thioether.

l '5. A photographic *process which comprises subjecting a photoexposed silver halide stratum and a silver-receptive stratumin superposed relation to an aqueous alkaline solution of silverhalide developing and dissolving 'redodecylthioether.

References Cited in' the file-of this patent UNITED STATES PATENTS Reppe et a1. ,Aug. 2, 19,38 Middleton Jan. 29, 1957 hall r 

1. THE HOTOGRAPHIC PROCESS OF APPLYING AN AQUEOUS ALKALINE SOILUTION OF A SILVER HALIDE DEVELOPER, A SILVER HALIDE SOLVENT AND AN ALKYL POLYOXYETHYLENE THIOETHER TO AN EXPOSED SILVER HALIDE STRATUM AND A SILVER-RECEPTIVE STRATUM IN SUPERPOSED RELATION IN ORDER TO PRODUCE A SILVER TRANSFER PRINT, SAID SOLUTION COMPRISING, BY TOTAL WEIGHT OF THE SOLUTION, FROM ABOUT 1 TO ABOUT 8% DEVELOPER, FROM ABOUT 0.3 TO ABOUT 10% SILVER HALIDE SOLVENT AND FROM ABOUT 0.33 TO ABOUT 3% OF SAID ALKYL POLYOXYETHYLENE THIOETHER. 